Disposable Sensor Device and Monitoring System

ABSTRACT

The invention relates to a disposable sensor device ( 51 ) for patient monitoring comprising a sensor ( 52 ) for providing an electric quantity based on a quantity to be detected, a first signal terminal ( 54 ) for providing a tap for the electric quantity, a first supply terminal ( 53 ) for supplying the sensor with an electrical supply quantity, a first connector for accommodating the first signal terminal ( 54 ) and the first supply terminal ( 53 ), a second signal terminal ( 56 ) for providing a further tap for the electric quantity, and a second connector for accommodating at least the second signal terminal ( 56 ). The invention further relates to a disposable sensor device for patient monitoring comprising a sensor ( 7 ) for providing an electric quantity based on a quantity to be detected; a first signal terminal ( 22 ) for providing a tap for the electric quantity; a first connector (A) for accommodating the first signal terminal, wherein the first connector (A) is provided with a trimming element (R 2 ) which simulates the influence of a selectively attachable first monitoring device ( 1 ) on a measuring of the electric quantity, wherein the trimming element (R 2 ) is electrically effective depending on a connector structure of a corresponding further connector (B, C) to be coupled with the first connector (A).

The present invention relates to disposable sensor devices for patientmonitoring such as an arterial blood pressure sensor device, a pulsecontour cardiac output device and the like. The present invention isfurther related to monitoring systems for such disposable sensordevices.

In patient monitoring there are situations wherein multiple monitoringdevices are needed which are dealing with the same parameter. Forexample, there may be some need to receive the respective signal by abedside monitor and by a portable device in parallel wherein both shouldbe able to read the parameter of interest. So far, each monitoringdevice, e.g. the bedside monitoring device and the portable measurementdevice, uses a separate sensor device. The multiple sensor devices maybe closely spaced to detect the same or at least similar results, ase.g. described in US 2006/0009699.

Mostly, the sensor device needs some kind of excitation voltage, i.e. asupply DC or AC voltage. Then, the sensor device delivers a detectorsignal which depends on the excitation voltage and the parameter whichis to be analyzed in the monitoring system.

To provide two sensor devices of the same kind for being read out by twodifferent monitoring devices leads to a bulky shape on the sensor'sside. Furthermore, the increased space volume may cause a worsefrequency response in case an AC excitation voltage is used. Even if thetwo sensor devices are closely spaced they are not located at the sameheart level such that in case of pressure sensor devices differentarterial pressure values would be obtained.

It is therefore an object of the present invention to provide adisposable sensor device and a monitoring system which allows to monitora measured parameter of patient by two or more monitoring devicesthereby avoiding the drawbacks of the prior art.

This object has been achieved by the disposable sensor devices accordingto claims 1 and 7 and the monitoring systems according to furtherindependent claims.

Further embodiments of the present invention are indicated in thedepending subclaims.

According to one aspect a disposable sensor device for patientmonitoring is provided. The disposable sensor device comprises a sensorfor providing an electric quantity based on a quantity to be detected, afirst signal terminal for providing a tap for the electric quantity, afirst supply terminal for supplying the sensor with an electrical supplyquantity, and a first connector for accommodating the first signalterminal and the first supply terminal. A second signal terminal forproviding a further tap for the electric quantity and a second connectorfor accommodating at least the second signal terminal are provided.

Furthermore, the sensor may be provided as a bridge circuit or any otheranalogue electric measurement circuit. The bridge circuit could be aWheatstone full or half bridge e.g. with resistors.

Moreover, the second connector further may include a second supplyterminal for tapping the supply quantity provided via the firstconnector.

According to another aspect, a monitoring system for patient monitoringis provided. The monitoring system comprises the above disposable sensordevice, a first monitoring device connectable to the first connector fortapping the electric quantity via the first signal terminal and forsupplying the electrical supply quantity via the first supply terminal.

A second monitoring device may be connectable to the second connectorfor tapping the electric quantity via the second signal terminal.

Furthermore, it may be provided a monitoring system comprising the abovedisposable sensor device, a first monitoring device connectable to thefirst connector for tapping the electric quantity via the first signalterminal and for supplying the electrical supply quantity via the firstsupply terminal, and a second monitoring device connectable to thesecond connector for tapping the electric quantity via the second signalterminal, wherein the second monitoring device is further adapted to tapthe electrical supply quantity supplied by the first monitoring devicevia the second supply terminal, wherein the second monitoring deviceincludes an excitation sensing circuit adapted to sense whether or notan electrical supply quantity is applied on the second supply terminaland to further supply an electrical supply quantity via the secondsupply terminal to the disposable sensor device in case no electricalsupply quantity can be sensed.

According to a further aspect a disposable sensor device for patientmonitoring is provided. The sensor device comprises a sensor forproviding an electric quantity based on a quantity to be detected, afirst signal terminal for providing a tap for the electric quantity, anda first connector for accommodating the first signal terminal. The firstconnector is provided with a trimming element which simulates theinfluence of a selectively attachable first monitoring device on ameasuring of the electric quantity, wherein the trimming element iselectrically effective depending on a connector structure of acorresponding further connector to be coupled with the first connector.

Moreover, the electric quantity may be applied between the first and asecond signal terminals of the first connector, wherein the trimmingelement is applied between the first and a third signal terminals of thefirst connector, wherein depending on the connector structure of thecorresponding further connector, either the first and second signalterminals are tapped and the third signal terminal remains untapped orthe first and a shortcut second and third signal terminals of the firstconnector are tapped.

Moreover, the sensor may comprise a Wheatstone-Bridge circuit or anyother analogue electric measurement circuit.

According to an embodiment the sensor has a pressure sensor formeasuring an arterial pressure of a patient.

A first excitation terminal may be provided in the first connector toapply an excitation voltage to the sensor. The excitation voltage may beapplied between the first and a second excitation terminals of the firstconnector, wherein a further trimming element is applied between thefirst and a third excitation terminal of the first connector, whereindepending on the connector structure of the corresponding furtherconnector, either the first and second excitation terminals areconnected with an excitation voltage and the third excitation terminalremains unconnected or the first and a shortcut second and thirdexcitation terminals are connected with the excitation voltage.

According to a further aspect a monitoring system for patient monitoringis provided. The monitoring system comprises a disposable sensor deviceas mentioned above and a first monitoring device for tapping theelectric quantity, having a second connector to match with the firstconnector, wherein the second connector has a connector structuredepending on which the trimming element of the first connector iselectrically effective.

Furthermore, the electric quantity may be applied between the first anda second signal terminal of the first connector, wherein the trimmingelement is applied between the first and a third signal terminals of thefirst connector, wherein the second connector has a terminal contact toshortcut the second and third signal terminals of the first connector ina plugged condition such that the trimming element is electricallyeffective.

Moreover, an excitation voltage may be applied between first and secondexcitation terminals of the first connector, wherein a further trimmingelement is applied between the first and a third excitation terminal ofthe first connector, wherein the second connector has an excitationterminal contact which is adapted to provide the excitation voltage fromthe first monitoring device and to shortcut the second and thirdexcitation terminal to both connect them with the excitation voltage ina plugged condition.

According to a further aspect a monitoring system for patient monitoringis provided. The monitoring system comprises a disposable sensor deviceas mentioned above, and a second monitoring device for tapping theelectric quantity, having a third intermediate connector to match withthe first connector, wherein the third connector has a connectorstructure such that, when the first and second connectors are in aplugged condition, the trimming element of the first connector iselectrically ineffective.

The electric quantity may be applied between the first and a secondsignal terminal of the first connector, wherein the trimming element isapplied between the first and a third signal terminal of the firstconnector, wherein the third connector has a terminal contact to onlycontact the second signal terminal but not the third signal terminal ofthe first connector in the plugged condition such that the trimmingelement is electrically ineffective.

An excitation voltage may be further applicable between first and secondexcitation terminals of the first connector, wherein a further trimmingelement is applied between the first and a third excitation terminal ofthe first connector, wherein the third connector has an excitationterminal contact which is adapted to provide the excitation voltage fromthe second monitoring device and to only contact the second excitationterminal but not the third excitation terminal of the first connector inthe plugged condition such that the further trimming element iselectrically ineffective.

According to a further aspect a monitoring system for patient monitoringis provided. The monitoring system comprises a disposable sensor deviceas mentioned above, a first monitoring device for tapping the electricquantity, having a second connector to match with the first connector,wherein the second connector has a connector structure such that, whenthe first and second connectors are in a plugged condition, the trimmingelement of the first connector is electrically effective, and a secondmonitoring device for tapping the electric quantity, having a thirdintermediate connector having two outlets to respectively match with thefirst and the second connector, wherein the second connector has aconnector structure such that, when the first and second connectors arein a plugged condition, the trimming element of the first connector iselectrically ineffective, wherein the third connector has a connectorstructure such that when the second and third connectors are in aplugged condition, the second monitoring device receives the electricalquantity passed through the third connector.

Furthermore, the electric quantity may be applied between the first anda second signal terminal of the first connector, wherein the trimmingelement is applied between the first and a third signal terminal of thefirst connector, wherein the second connector has a terminal contactwhich is adapted to shortcut the second and third signal terminals ofthe first connector in the plugged condition of the first and secondconnectors such that the trimming element is electrically effective,wherein the third connector has a terminal contact which is adapted toonly contact the second signal terminal but not the third signalterminal of the first connector in the plugged condition of the firstand third connector such that the trimming element is electricallyineffective.

An excitation voltage may be applicable between first and secondexcitation terminals of the first connector, wherein a further trimmingelement is applied between the first and a third excitation terminal ofthe first connector, wherein the second connector has an excitationterminal contact which is adapted to shortcut the second and thirdexcitation terminals to both connect them with the excitation voltage ina plugged condition, wherein the third connector has an excitationterminal contact which is adapted to only contact the second excitationterminal but not the third excitation terminal of the first connector inthe plugged condition of the first and the third connector such that thefurther trimming element is electrically ineffective, wherein the thirdconnector further has a connector structure such that when the first,second and third connectors are in a plugged condition, the secondmonitoring device is adapted to supply the excitation voltage to thesensor via the third connector.

An excitation supply unit may be provided in the second monitoring unitwhich is adapted to detect, when the first and third connector are inthe connected condition, an appliance of an excitation voltage on thefirst and second excitation terminals of the first connector, and incase that no excitation voltage is applied on the first and secondexcitation terminals of the first connector the excitation supply unitsupplies an excitation voltage via the third connector to the firstconnector otherwise the excitation supply unit does not supply anyexcitation voltage.

Moreover, the second monitoring device may be adapted to monitor thequantity to be detected for the case the trimming element iselectrically effective.

Preferred embodiments of the present invention are described in detailin conjunction with the accompanying drawings, in which same referencesigns indicated elements having the same or similar functionality and inwhich:

FIG. 1 shows schematically a configuration of a monitoring systemaccording to an embodiment of the present invention;

FIG. 2 shows schematically the electrical interconnections between thebedside monitor and the disposable pressure transducer;

FIG. 3 shows schematically a further configuration of a monitoringsystem according to the embodiment of FIG. 1;

FIG. 4 shows schematically the electrical interconnections between thebedside monitor, the portable measurement device, and the disposablepressure transducer;

FIG. 5 schematically illustrates the terminals of the transducer plug A;

FIG. 6 schematically illustrates the terminals of the intermediate plugB;

FIG. 7 schematically illustrates the terminals of the BSM plug C;

FIG. 8 shows the BSM plug c, the intermediate plug B and the transducerplug A in a connected condition;

FIG. 9 shows the BSM plug C and the transducer plug A in a connectedcondition; and

FIG. 10 shows a disposable sensor device and a monitoring systemaccording to a further embodiment.

In FIG. 1 a possible configuration of a monitoring system in a firstconfiguration is disclosed. The monitoring system includes as a firstmonitoring device a bedside monitor (BSM) 1 for receiving, storingand/or visualizing patient-related data of a patient P. In theillustrated example, the bedside monitor 1 is directly coupled with anarterial pressure module 2 which receives a sensor signal from adisposable pressure transducer (DPT) 7 as a sensor via a cableconnection. The arterial pressure module 2 receives the sensor signalsand provides a communication of pressure information obtained with thesensor signal to the bedside monitor 1.

An arterial catheter 9 is placed inside the patient P and is coupledwith a reservoir 11 via a respective tubing 5. The tubing 5 isconfigured to supply an infusion liquid from the reservoir 11 to thepatient's body. The tubing 5 is lead through an organizer plate 8 whichis preferably located at mid-chest level of the patient. A stop cock 17for disconnecting the reservoir 11 from the catheter 9 is placed on theorganizer plate 8. In proximity to the stop cock 17 at the mid-chestlevel a pressure transducer 7 as a sensor device is placed at the tubing5 to detect the pressure of the infusion liquid within the tubing 5. Theinfusion liquid in the tubing 5 transmits the blood pressure in thepatient's arterial vessels to the pressure transducer 7 at the organizerplate 8.

The cable connection between the bedside monitor 1 and the pressuretransducer 7 includes a connection cable 3 which is connected orconnectable to the bedside monitor 1 and which is provided with a thirdconnector C, further referenced as BSM plug C. The pressure transducer 7is provided with a pressure transducer cable 6 and provided with a firstconnector A further referred to as transducer plug A. Transducer plug Aand BSM plug C can be coupled to provide electrical connections betweenthe bedside monitor 1 and the pressure transducer 7.

In FIG. 2 it is schematically shown the electrical interconnectionsbetween the bedside monitor 1 and the disposable pressure transducer 7as well as a structure of an exemplary pressure transducer. In the givenexample, the disposable pressure transducer 7 has a number of fourpressure detecting elements 12 which are coupled to form a Wheatstonebridge as it is well-known in the art, to increase detectionsensitivity. The Wheatstone bridge receives an excitation voltage viaexcitation lines E+, E− which may be a DC voltage in case of resistivedetecting elements 12 and which may be an AC voltage having a predefinedoscillation frequency and magnitude in case the detecting elements 12are capacitive or inductive detecting elements. From the output nodes ofthe Wheatstone bridge sensor signals S+, S− are tapped via signal linesby the bedside monitor 1. The sensor signals S+, S− depend on thepressure to be detected according to the states of the detectingelements 12 as well as on the excitation voltage. Instead of pressuretransducer any kind of sensors which provide a detectable sensor signalcan be applied with each embodiment of the present invention.

In cases of a situation wherein in patient monitoring multiplemeasurement devices are needed to e.g. detect the blood pressure of thepatient P the monitoring system proposes a way to further use thepressure transducer 7 as the sensor device for a portable measurementdevice 4 which is to be further connected with the pressure transducer7. FIG. 3 shows schematically a second configuration of the monitoringsystem wherein the portable measuring device 4 is connected with thepressure transducer 7.

The portable measurement device 4 is provided via a measurement cablewith an intermediate connector B further referred to as intermediateplug B. The measurement cable includes as described above excitationlines and signal lines to supply the pressure transducer 7 and toreceive the sensor signal from the pressure transducer 7, respectively.The intermediate plug B is adapted to couple the portable measurementdevice 4 with the cable connection between the bedside monitor 1 and thepressure transducer 7. The intermediate plug B is coupled in between theBSM plug C and the transducer plug A.

FIG. 4 schematically shows the electrical coupling of the pressuretransducer 7 with both the bedside monitor 1 and the portablemeasurement device 4. To avoid the case that both the bedside monitor 1and the portable measurement device 4 provides an excitation voltage forthe pressure transducer 7 preferably at least the portable measurementdevice 4 can include a excitation sensing circuit 16 which detects viathe excitation lines whether an excitation voltage is already suppliedto the pressure transducer 7 and if an excitation voltage is alreadysupplied to the pressure transducer 7 no excitation voltage is suppliedby the portable measurement device 4. Otherwise the portable measurementdevice 4 supplies an excitation voltage to the pressure transducer 7 viaexcitation lines.

In general, each of the monitoring devices 1, 4 connected to thepressure transducer 7 may be configured to deliver an excitation voltageto the pressure transducer 7 if it is not present. In this configurationall monitoring devices to be coupled to the detector device could bebuilt up equally and the monitoring device which provides the excitationto the detector device is defined on the fly.

As mentioned above, the pressure transducer 7 has to function with bothconfigurations either connected to a bedside monitor 1 only or connectedsimultaneously to the bedside monitor 1 and the portable measuringdevice 4 in parallel.

The connection of the pressure transducer 7 to the bedside monitor 1 maybe mandatory. Then, the pressure transducer 7 gets its excitationvoltage from the bedside monitor 1. The portable measurement device 4detects the excitation voltage and measures the sensor signal. However,the pressure reading on the bedside monitor 1 may under no circumstancesbe influenced by a parallel connection of the portable measurementdevice 4. As the portable measurement device 4 includes an inputresistance the sensor signal is influenced by the input resistance ofthe sensing ports of the portable measurement device 4 if the portablemeasurement device 4 is connected to the cable connection. By providingthe pressure transducer 7 with a Wheatstone bridge the sensitivity withregard to input resistances of portable measurement device 4 and/or thebedside monitor 1 are already substantially decreased. Furthermore,according to the present embodiment the connectors, i.e. the transducerplug A, the BSM plug C and the intermediate plug B of the portablemeasurement device 4 are provided with a structure which allows thebedside monitor 1 to detect the sensor signal from the pressuretransducer 7 under the same conditions either with the portablemeasurement device 4 connected or not.

In FIG. 5 the terminals of the transducer plug A are schematicallyshown. The terminals for the provision of the excitation voltages to thepressure transducer 7 are referred to as first and second excitationterminals 20 and 21, 25 respectively, the signal terminals for readingthe sensor signals from the pressure transducer 7 are indicated as firstand second signal terminals 22 and 23, respectively. The transducer plugA includes a first trimming resistance R1 and a second trimmingresistance R2. The first trimming resistant is coupled between the firstexcitation terminal 20 and a third excitation voltage terminal 24. Thesecond trimming resistance R2 is coupled between the first signalterminal 22 and a third signal terminal 25. The third excitationterminal 24 and the third signal terminal 25 are open that means theyare not contacted in a non-contacting condition of the transducer plugA. Furthermore, the second excitation terminal 21 and the thirdexcitation terminal 24 as well as the second signal terminal 23 and thethird signal terminal 25 are fully isolated from each other.

The first and the second trimming resistances R1, R2 (impedances) haverespective values that simulate the resistances (impedances) of theportable measurement device 4 if connected to the BSM plug A. Therefore,the value of the first trimming resistance R1 is selected to correspondto the internal resistance between the excitation terminal contacts ofthe portable measurement device 4. The value of the second trimmingresistance R2 is selected to correspond to the internal input resistanceof detection signal contacts of the portable measurement device 4 forreceiving the sensor signal.

In FIG. 6 the internal structure of the intermediate plug B is shown.The intermediate plug B provides interconnection wiring 33 for each ofthe excitation voltages E+, E− and each of the sensor signals S+, S−which are further branched to the portable measurement device 4 suchthat the portable measurement device 4 can provide an excitationvoltage, receive an excitation voltage and may tap the sensor signalfrom the pressure transducer 7 via the transducer plug A. For couplingwith the transducer plug A, the intermediate plug B has first contacts34 of a first outlet 31. For coupling with the BSM plug C, theintermediate plug B has second contacts 35 of a second outlet 32. Thefirst outlet 31 is structurally adapted to be only connectable to thetransducer plug A wherein the second outlet 32 of the intermediate plugB is structurally adapted to be only connectable with the BSM plug C.Thereby, faulty interconnections between the devices can be avoided.

FIG. 7 illustrates the structure of the BSM plug C. The respectiveexcitation lines E+, E− and sensor signal lines S+, S− connected withthe bedside monitor 1 are coupled to respective contacts 41.

The BSM plug C can be connected with the second outlet 32 of theintermediate plug B such that the interconnection wiring are in contactwith the respective excitation lines E+, E− and the signal lines S+, S−of the BSM cable. The contacts 41 of the BSM plug C can be provided aslong contact pads which are able to simultaneously contact, in a pluggedcondition with plug A, the second and third excitation terminal 21, 24as well as the second and third signal terminals 23 and 25, 15respectively.

As shown in FIG. 8, the BSM plug C, the intermediate plug B and thetransducer plug A are connected with each other. An electricalinterconnection of the excitation lines and signal lines between thetransducer plug A and the BSM plug C is provided by the interconnectionwiring 33 in the intermediate plug B. Furthermore the intermediate plugB provides the electrical connection of the interconnection wiring 33with the portable measurement device 4 such that the portablemeasurement device 4 receives the excitation voltage as well as thesensor signals provided by the pressure transducer 7. When coupling thefirst outlet 31 of the intermediate plug B to the transducer plug A thefirst contacts 34 of the intermediate plug B do only connect the firstand second excitation terminals 20, 21 and the first and second signal30 terminals 22, 23 of the transducer plug A, respectively. The thirdexcitation terminal 24 and the third signal terminal 25 are notelectrically contacted. One reason therefore is that between the firstand second excitation terminals 20 and 21 of the transducer plug A avalue of the first trimming resistance R1 is provided as the inputresistance of the portable measurement device 4. Therefore the firsttrimming resistance R1 should not be electrically effective within thetransducer plug A. The same is for the second trimming resistor R2 whichalso is electrically ineffective as the portable measurement device 4 isin electrical connection with the first and second signal terminals 22and 23. To summarize, the trimming resistors (impedances) R1, R2provided within the transducer plug A are made electrically ineffectiveas they are not necessary to simulate the internal resistances of theportable measurement device 4 as it is already connected.

However, as shown in the configuration of FIG. 9 the BSM plug C isconfigured to be also connected with the transducer plug A. In such aconfiguration contacts of the BSM plug C contacts the second excitationvoltage terminal 21 and the second signal terminal 23 in the mannerdescribed with regard to the connection with the intermediate plug B.However, the BSM plug C further provides an interconnection (shortcut)between the second excitation terminal 21 and the third excitationvoltage terminal 24 as well as between the second signal terminal 23 andthe third signal terminal 25. The shortcut make the first and secondtrimming resistors R1 and R2 electrically effective such that betweenthe first and second excitation terminals 20, 21 as well as it been thefirst and second signal terminals 22 and 23 the trimming resistances(impedances) R1, R2 are applied which simulate the state of a connectionof the portable measurement device 4 although it is not connected to themonitoring system in this configuration. As there is no portablemeasurement device 4 connected the trimming resistors R1, R2 areelectrically effective.

The plugs A, B, C can be provided with terminals and contacts configuredas simple contact pads, pins and the like which can be contacted withcorresponding terminals and contacts which may be adapted like flexiblecontact beams, spring-like contacts and the like.

In general, features for connectors A, B, and C should fulfill followingrequirements:

-   -   the transducer connector can be connected either with a first        outlet of the intermediate connector B or with an monitoring        device connector each for connecting the detector device with a        respective monitoring device;    -   a second outlet of the intermediate connector is only        connectable with a monitoring device connector but not with the        transducer connector;    -   in case the transducer connector is directly connected with a        monitoring device connector, trimming resistances are made        electrically effective and coupled with at least one of        excitation terminals and signal terminals of the transducer        connector;    -   in case the intermediate connector is connected with the        transducer connector the trimming resistances R1, R2 are not        made electrically effective.

The embodiments of the present invention provide at least one or more ofthe following advantages:

-   -   an arterial blood pressure waveform can be measured by two or        more monitoring devices in parallel using only one sensor    -   known disadvantages of curve-damping by using two sensors which        would result in a larger dead space within one pressure sensor        are ruled out;    -   the pressure of exactly the same heart level can be recorded by        two monitoring devices;    -   the pressure transducer can be trimmed to correct impedance        conditions independently from whether it is connected to the        bedside monitor alone or to both the bedside monitor and the        portable measurement device in parallel;    -   the pressure transducer is only provided with one transducer        plug which only has one outlet so safety requirements during        defibrillation are fulfilled. In other words no open connection        exists.

The principle of the present invention can be used for any passiveanalogue sensor like e.g. a thermostat for temperature measurement, aconductivity sensor or an electrical impedance sensor as long theadditional measurement device has an adapted interface and its innerresistance (impedance) is known as constant.

Further to the embodiment of the monitoring system of FIGS. 1 and 3 thepressure transducer 7 can also be applied close to the catheter 9.Moreover, further connectors can be provided within the connectioncables of all monitoring devices and the sensor device.

In the above-mentioned embodiment preferably both the bedside monitor 1and the portable measurement device 4 are provided with a source for anexcitation voltage. Both devices may be provided with excitation sensingcircuits to decouple the excitation voltage if an excitation voltage isalready present on the excitation lines in the cable connection betweenthe respective measurement device and the pressure transducer 7.However, as portable measurement devices usually are battery powered itis preferred that the portable measurement device is the device whichdecouples the excitation voltage from the transducer in case the bedsidemonitor 1 may provide the excitation voltage. In other words, it can beprovided that the provision of the excitation voltage by the bedsidemonitor 1 has priority to the provision of the excitation voltage by theportable measurement device 4.

Another embodiment is shown in FIG. 10, wherein another structure of adisposable sensor device in a monitoring system is depicted. Themonitoring system 50 of FIG. 10 includes a disposable sensor device 51having a transducer 52 and a connector 55 having a first connector portto accommodate two first signal terminals 54 and two first supplyterminals 53 as known from the embodiments described above. Preferably,the transducer 52 and the connector 55 may be integrally formed,however, they can also be connected together via a suitable cable. Thecircuitry of the transducer 52 (e.g. Wheatstone Bridge) may be similaror the same as of the above embodiments. Instead of a Wheatstone bridgea simple voltage divider comprising a series connection of two pressuresensors or of one pressure sensor and one or more resistors. A tapbetween the pressure sensors or between the pressure sensor and theresistors provides a single sensor signal based on the detectedpressure.

The connector 55 is further provided with a second connector portaccommodating second signal terminals 56 and, as an optional feature,second supply terminals 57, wherein each of the first supply terminals53 is electrically interconnected with a respective second supplyterminal 57 (if existing) and each of the first signal terminals 54 iselectrically interconnected with a respective second signal terminal 56.

To the first connector port a first plug 63 may be connected toelectrically connect a first monitoring device 60 to the disposablesensor device 51 via the first supply lines 61 and the first signallines 62. Normally, the first monitoring device 60 provides anexcitation voltage via the first supply lines to the disposable sensordevice 51. The excitation voltage can be set as already explained withrespect to the above embodiments.

The first monitoring device 60 receives a sensor signal via the firstsignal lines 62 from the disposable sensor device 51 to detect thequantity to be measured, such as the blood pressure of the patient, asalready described above.

To the second connector port a second plug 73 may be connected toconnect a second monitoring device 70 to the disposable sensor device 51via the second supply lines 71 and the second signal lines 72. Thesecond monitoring device 70 preferably merely receives a sensor signalvia the second 20 signal lines 62 from the disposable sensor device 51to detect the quantity to be measured, but without supplying any supplyto the disposable pressure device. In that case no supply lines need tobe provided between the second plug 73 and the second monitoring device70. Thereby, the second monitoring device 70 can be provided without asupply source for driving the sensor device 51 and the design effort forthe second monitoring device 70 can be reduced.

According to another embodiment, the second monitoring device 70 may beprovided with an excitation sensing circuit 74 which can be connectedvia second supply lines with the second supply terminals in theconnector 55 of the disposable sensor device 51. The excitation sensingcircuit 74 is adapted to detect whether or not an excitation is providedfrom the first monitoring device 60 via the first supply terminals 53and supplies an excitation voltage by its own in case no excitationvoltage can be detected via the second supply lines 71.

In case the transducer merely includes a voltage divider or anothercircuit instead of a Wheatstone bridge only one or more than two firstand second signal lines 62, 72 as well as 10 the respective connectorsmay be provided.

REFERENCE NUMERALS

1 Bedside monitor

2 Arterial pressure module

3 Cable

4 Portable measurement device

5 Tubing

6 Pressure transducer cable

7 Pressure transducer

8 Organizer plate

9 Catheter

11 Reservoir

12 Pressure detecting elements

16 Excitation sensing circuit

17 Stop cock

20 First excitation terminals

21 Second excitation terminals

22 First detection signal

23 Second detection signal

24 Third excitation terminals

25 Third detection signal

31 First outlet

32 Second outlet

33 Interconnection wiring

34 First contacts

35 Second contacts

41 Contacts

51 Disposable sensor device

52 Sensor

53 First supply terminal

54 First signal terminal

55 Connector

56 Second signal terminal

57 Second supply terminal

60 First monitoring device

61 First supply lines

62 First signal lines

63 First plug

70 Second monitoring device

71 First supply lines

72 First signal lines

73 Second plug

74 Excitation detection circuit

1. A disposable sensor device for patient monitoring comprising: asensor for providing an electric quantity based on a quantity to bedetected; a first signal terminal for providing a tap for the electricquantity; a first supply terminal for supplying the sensor with anelectrical supply quantity; a first connector for accommodating thefirst signal terminal and the first supply terminal; a second signalterminal for providing a further tap for the electric quantity; a secondconnector for accommodating at least the second signal terminal.
 2. Asensor device according to claim 1, wherein the sensor is provided in abridge circuit.
 3. A sensor device according to claim 1, wherein thesecond connector further includes a second supply terminal for tappingthe supply quantity provided via the first connector.
 4. A monitoringsystem for patient monitoring comprising: a disposable sensor deviceaccording to claim 1; and a first monitoring device connectable to thefirst connector for tapping the electric quantity via the first signalterminal and for supplying the electrical supply quantity via the firstsupply terminal.
 5. A monitoring system according to claim 4 furthercomprising: a second monitoring device connectable to the secondconnector for tapping the electric quantity via the second signalterminal.
 6. A monitoring system for patient monitoring comprising: adisposable sensor device according to claim 3; a first monitoring deviceconnectable to the first connector for tapping the electric quantity viathe first signal terminal and for supplying the electrical supplyquantity via the first supply terminal; a second monitoring deviceconnectable to the second connector for tapping the electric quantityvia the second signal terminal; wherein the second monitoring device isfurther adapted to tap the electrical supply quantity supplied by thefirst monitoring device via the second supply terminal; and wherein thesecond monitoring device includes an excitation sensing circuit adaptedto sense whether or not an electrical supply quantity is applied on thesecond supply terminal and to further supply an electrical supplyquantity via the second supply terminal to the disposable sensor devicein case no electrical supply quantity is sensed.